"It is white and the human cartilage cells are alive and producing what they are supposed to," said researcher Lars Kölby.

An illustration shows the growth of blood vessels through the cartilage construct after 3D printed cartilage is implanted in a mouse model. Photo by Philip Krantz/Chalmers University of Technology

March 23 (UPI) -- Scientists in Sweden successfully implanted 3D bioprinted human cartilage cells in an animal model. Researchers hope the breakthrough paves the way for the technology's use in human patients.

"This is the first time anyone has printed human-derived cartilage cells, implanted them in an animal model and induced them to grow," Paul Gatenholm, professor of biopolymer technology at Chalmers University of Technology in Gothenburg, said in a news release.

The bioink used to print the cartilage "construct," a woven, lattice-like structure, was made by infusing a nanocellulose hydrogel with human-derived cartilage cells. After it was printed, scientists implanted the construct inside mice.

Last year, the research team presented the structural integrity of their human cell-derived, 3D-printed cartilage at the 251st National Meeting and Exposition of the American Chemical Society.

During the latest tests, researchers observed cartilage growth and blood vessel formation. They also showed the addition of stem cells further aided new cartilage growth.

"What we see after 60 days is something that begins to resemble cartilage. It is white and the human cartilage cells are alive and producing what they are supposed to," said Lars Kölby, senior lecturer at Sahlgrenska Academy at the University of Gothenburg. "We have also been able to stimulate the cartilage cells by adding stem cells, which clearly promoted further cell division."

"We now have proof that the 3D printed hydrogel with cells can be implanted," Gatenholm said. "It grows in mice and, in addition, blood vessels have formed in it."

The scientists say they're still a ways from growing and implanting human organs, but they're making progress.

"This is how you have to work when it comes to this kind of pioneering activity: one small step at a time" Gatenholm said. "Our results are not a revolution -- but they are a gratifying part of an evolution!"